Gold-saving machine.



R..S. BASSETT. GOLD SAVING MACHINE. APPLICATION FILED MAR.19,L912.

Patented Jan. 14, 1913.

2 "0/ m ym M MO R v w UNITED STATES PENT OFFICE.

ROBERT SMITH BASSETT, OF MINNEAPOLIS, MINNESOTA, ASSIGNOR TO OCEAN BEACH GOLD PLATINUM DREDGE COMPANY, A CORPORATION.

GOLD-SAVING MACHINE.

Specification of Letters latent.

Application filed March 19, 191a Serial No. 684,864.

at Minneapolis, in the county of Hennep-in and State of Minnesota, have invented cer 'tain new and useful Improvements in Gold-- Saving Machines, of which the following is a specification.

My invention relates to gold saving inachines and particularly to machines of that type in which the gold is collected in a riflie at the bottom of the sluice-box through which the mixed gravel and water are run.

The object of my invention is to provide.

a device for the above purpose in which rifile bars of peculiar shape are arranged so as to cause whirling eddies between'the bars: which will permit settling of even the finest flour gold ;while carrying away the lighter material, without using a greater length of.

riflle than is ordinarily employed in saving only the coarser gold. v

It has long been k-nownthat 1n certam .types of placers a large amount of gold ex-- ists in a very finely divided state, sometimes called flour gold. In attempting to collect this gold sluice-boxes several hundred feet long have been employed. In such cases all of the coarser gold will be collected inthe first eight or ten feet of the riflle and some of the flour gold will be collected thereafter,

although with the best systems a very considerable percentage of the flour gold runs But with the long riflle structure it is usually the case that the concentrates toward the discharge end of the riflle are so poor in gold and what gold there is is so mixed with black sand and other minerals from which it may be separated only with extreme difiiculty, that the expense of recovering the gold from such concentrates may be greater than the'value of the gold recovered. With the new rifile which I have invented I am able to obtain fully as high if not higher saving of flour gold in an ordinary twelve foot sluice-box as has been secured by the use of the aforesaid sluice-boxes and riflles extended several hundred feet in length, and, of course,-the separation of the gold from the concentrate willbe a matter of no more expense than the separation of the coarse gold from thefir'st' twelve feet of concentrates of the said long These objects I accomplish by means of.

riflle bars formed with top surfaces and positioned relatively so that as the stream of gravel-bearing water passes over the rifile bars the peculiar slope of said top surfaces will give the water or the gravel-bearing part of it next to the rifile a peculiar whirl ingmovement which gives opportunity for the flour gold to sift through edgewise and become settled in the concentrate while the lighter material of the gold-bearing sand is lifted out from betweenthe riflles.

Patented 'J an. 14,1913.

The full objects and advantages of my invention will appear in connection with the detailed description thereof and the novelty is particularly pointed out in the claims.

In the drawings, illustrating the application of my invention in one form,-Figure 1 is a plan view of a part of a sluice-box employing a ritfie constructed in accordance with my invention. Fig. 2 is a broken longitudinal sectional elevationon line 1 l of,

Fig. 1.

The sluice-box is of usual construction consisting of a bottom member 10 supported by cross bars 11 and legs 12 of such length, relatively, that the bottom 10 is given a downward inclin e,which in the practice of my invention may be quite sharp and greater than is customary with other devices of this general character. The sides of the sluicebox 13 and 14 are of usual construction and a. head 15 is provided into which leads a chute or trough 16 for conveying thesand and water into the sluice-box.

- Upon the bottom 10 is laid a piece of tex tileor other fabric 17, a very go'od fabric for the purpose being cocoa matting, and

in the sluice-box is the improved riflie which I have devised. As shown this comprises a series of transversebars 18, each bar being triangular in cross section. strungupon threaded rods 19 which-pass through'openingstherein, the bars being properly spaced by means of washers 20, said washers having obliquelydisposed end faces so that when the rods are screwed up the bars will be rigidly'connected together and held ,with their corresponding edges falling in common planes. VVheIf, therefore, the riffle. is placed'upon the bottom of the sluice-box or on the cocoa mattin 17 with the most acute anglededges of e bars in contact therewith the other acute angled edges of the bars will have the highest parts These bars are,

thereof falling in a planeparallel with the plane of the bottom of the sluice-box, the shortest faces 23 of the bars extending back from the highest edges obliquely 'or at an angle to the common plane passing through said edges or the plane of the bottom of the sluice-box. The longest sides 21 of the rifiie bars are thus turned away from the direction of travel of the water in the sluice-box and inclined forward at a sharp angle while the intermediate sides 22 extend upwardly from the bottom of the sluice-box at a much less acute angle, thereby providing between pairs of rifile bars chambers which are considerably wider at the bottom than at the top and which have a much longer wall on the side away from the direction of travel of the stream than on the side which fronts that direction of travel. The dead water space or settling space between the bars is therefore relatively very much increased, especially toward the bottoms of these chambers where it is of most value. The stream of material passing over the rifile includes water mostly at the top and grave] or sand at the bottom, which will comprise approximately two layers, the heavier lowest down and the lighter above, the heavier particles in the upper of these two layers-constantly gravitating toward the lower layer. Owing to the slope of the faces 23 the riflle bars, at an angle to the plane of the bottom of the sluice-box or the plane of forward movement of the stream, the meeting point of walls 22 and 23 will be such as normally to divide this sheet of material, the lighter sliding up the faces 23 and the heavier being caused to roll or whirl by the drop over the upper edges and the impact with. the walls 22. This turning or whirling movement is in a'vertical plane and throws back the lighter particles into the layer which is carried over the faces 23 and gives opportunlty for the finely divided lenticular particlesof floun gold to gravitate edgewise to the bottom of the chambers between the riflie bars where it will-be trapped with the concentrates, especially beneath the forwardly sloping walls 21.

The usual construction of a rifiie for use in gold saving devices of this character is to provide flat faced blocks secured in relat ve position so that there are spaces between the blocks about equal to the top faces of the blocks, the blocks usually being about an inch square in cross section and the spaces between the blocks about 'one inch, so that in the common twelve-foot sluice-box there w1ll be seventy-two such riflle bars. In my construction I have found a practical size to be bars having the longer faces 21 one inch, the faces 22 three-quarters of an inch and the faces 23 approximately threeeighths of an inch. The bars are placed apart exactly one inch so that there will be a large part of the one hundred and forty-four of such rifile bars in a twelve-foot sluice box instead of seventy-two as in the common type, and although the aggregate of the dividing surfaces 23 of my ritfle will be considerably less than the aggregate of the top surfaces of the old style riflie,, owing to the angular slant of these faces with respect to the plane of the top edges of the rifiie bars and of the bottom of the sluice box the effective separating value of the faces 23 will be greater face for face than that in the common sluicebox, while the fact that there are tw1ce as many of such separating faces and that the dead water chambers between the bars are greater causes my rifiie as regards the upper faces only to be enormously more efiiclent than the old style riffle. There are also twice as many settling pockets between the riflie bars and owing to the relation of the walls 21 and 22, so that these pockets are narrower at the top than at the bottom and ocket is overhung by the walls 21 of the rii e bars, the dead water settling space in each of these pockets is both greater and more efficient than in the usual form of riflle.

An attempt has been made to indicate by means of dotted lines the course which the stream of gravel-charged water takes 1n passing over my ritlie. The overhang of the upper edges, the fact that these edges are sharp and the angular slope of the faces 23 up to these edges all have the eflect of cansing the stream to dip sharply as it passes over the edges and striking agalnst the face 22 to curl over and under in a smooth vertical whirl without any boils or whirlpool currents, which have a tendency to suck up matter from the bottom of the compartments between the rifiie bars. This action results in constantly breaking up the stream of matter gravitating over the riflle toward the discharge end of the sluice-box, the breaking up resulting in the lighter material always being thrown to the upper layer and the heavier particles having opportunity to gravitate to the lower layer and from there into the dead water settling spaces. The gold, of course, is likely to be the heaviest material carried, and the only reason that itis not always possible to effect separation is because fine or flour gold, although divided into extremely minute particles, does not exist in granular form but in tiny flakes or scales which present a large surface in proportion to their mass to the action of the water currents, These scales gravitate very readily edgewise, but if suspended in water with the flat sides down they pass through the same very slowly. The dividing and breaking up action of my rifiie, however, constantly tends to change the positions of these little gold particles and get them on edge, when they gravitate down beneath the ,overhanging walls 21 and become entangled in the concentrates, from which ,they may be recovered with the coarser old.

In or er to regulate the incoming stream of water from the chute 16 so as to spread the same evenly and particularly to enable the mineral sands to be accumulated at once into the layers heretofore mentioned I suspend a gate 24 b means of arms 25 secured to the end said gate and extending at an oblique angle thereto, the arms being pivoted at 26 and 27 to the side walls 13 and 14 of the sluice-box, and the arrangement being such that the lower surface of the gate 24 will extend downwardly at an oblique angle to the lane extending through the highest points of the rifle bars, said angle being oppositely disposed from, that 'of the top surfaces 23 of the rifle bars. The gate 24 is thus positioned to float upon the. incoming stream of gravel-charged water. It may be lifted thereby but will constantly tend to control and regulate the flow and to produce quickly the said layering of the solid contents of the water.

.I have given the operation of my device and the principles upon which it works very fully. It is simple and cheap in construction, can be made in any desired size and applied to any sluice-box construction in many different sorts of gold saving'systems.

I claim: 7 1. In combination, a sluice, a rifle there;

for comprising .a series of bars, each bar having a cross sectional outline consisting of an obtuse triangle, means independent of the sluice for holding said bars with the walls parallel and corresponding edges in parallel planes and with none of the sides falling in the planes of'the edges, so that when the apices of the two longest sides rest upon the bottom of the sluice the shorter side will be turned toward and reversely inclined to a direction fall of the current.

2. A gold-saving machinecomprisin an inclined sluice-box, a strip of fabric oose on the bottom of the sluice-box, a rifle formed of transverse bars removably positioned in the sluice-box with the lower edges of the bars engaging the fabric, said bars being held with corresponding sides parallel and the highest parts of said bars being held in a common plane arallel with the bottom extend from the highest part thereof ob-' liquely to the sluice-box. 4. A gold saving machine comprising an plane of the bottom of the inclined sluice-box and a rifle therein, said rifle being formed with a series of transverse bars triangular in cross section, the bars, resting with their most acute angled edges engaging the bottom, their longest sides turned down and slopin at an angle to the bottom, and shortest si es turned up and extending backwardly from the edge formed by their junction with the longest sides obliquely to the plane of the bottom of the sluice-box.

5. A gold-saving machine comprising an inclined sluice-box and a rifle therein, a sheet of fabric removably positioned on the bottom of the sluice-box, said rifle being formed of a series of transverse bars triangularin cross section and having the most acutely angular edges thereof resting upon the fabric, their longest sides turned down and sloping at an angle to the bottom, and shortest sides turned up and extending backwardly from the edge formedby their junc tion with the longest sides obliquely to the plane of the bottom of the sluice-box.

In testimony whereof I aflx'my signature in presence of two witnesses.

B. SMITH BASSETT.

Witnesses H. A; BOWMAN,

- F. A. WHrra EY. 

